The present invention relates to a process for producing an optically active liquid crystalline polymer compound useful as an optical material or a high strength material.
Optically active liquid crystalline polymer compounds have various applications such as high strength materials or optical materials and thus are highly available. Form the viewpoint of industrial utilization, the production cost of such polymer compounds is so important that they can be produced by an inexpensive process such as a synthesis method using melt-polycondensation which may be efficiently conducted even in the absence of a solvent.
Generally, the majority of liquid crystalline polymer compounds comprise an aromatic dicarboxylic acid unit, an aromatic diol unit and an aromatic oxycarboxylic acid unit. Therefore, after the phenolic hydroxyl groups of such compounds are usually acetylated with acetic anhydride in a reaction vessel, the compounds are subjected to melt-polycondensation in the same reaction vessel.
The production of a liquid crystalline polymer compound using a solution technique or method is industrially disadvantageous because of less amount of producible polymers per reactor, involvement of a complex step for activating reaction products and necessity of an after-treatment. The oxycarboxylic acid unit is not suitable for the reaction using a solution because the unit is likely to be blocked by itself. Therefore, there is a limit to the types of producible polymers with this solution technique.
That is, when an optically active liquid crystalline polymer compound is produced by introducing an optically active compound having an aliphatic hydroxyl group to a liquid crystalline polymer compound, there has been a problem that there are many restrictions in synthesis. For example, Patent Documents 1 and 2 below each disclose a method of producing a cholesteric film using a polyester wherein materials are mainly prepared by blending a liquid crystalline polymer as the base material with an optically active polymer or compound. Patent Document 3 discloses a side chain optically active polymer which is produced through a complex multi-steps. Therefore, in such a situation as described, there has been demanded a process wherein an optically active liquid crystalline polymer can be easily produced.                Patent Document 1: Japanese Patent Laid-Open Publication No. 5-61039        Patent Document 2: Japanese Patent Laid-Open Publication No. 6-186534        Patent Document 3: Japanese Patent Laid-Open Publication No. 10-158268        